(a) Field of the Invention
The present invention relates to a liquid crystal display device including an array substrate which is provided with contact holes and a counter substrate which is provided with spacers and aligned with the array substrate. In particular, it relates to measures to prevent the formation of an uneven gap between the substrates derived from the spacers which have got into the contact holes.
(b) Description of Related Art
In general, liquid crystal display devices include a plurality of spacers provided between an array substrate and a counter substrate to give a uniform gap between the substrates. If spherical spacers are provided between the substrates by spraying, cohesion of the spacers is likely to occur. Therefore, in recent years, a substrate provided with integral columnar spacers is commonly employed as one of the substrates. For example, Japanese Unexamined Patent Publication No. H4-122914 describes (see page 2 of the official gazette and FIG. 2) a liquid crystal display device, in which integral spacers are formed on a color filter substrate (counter substrate) provided with counter electrodes.
From the viewpoint of preventing irregular display derived from the presence of the spacers, it is preferred to arrange the spacers at positions corresponding to supplementary capacitor bus lines (hereinafter may be referred to as Cs bus lines) which are larger in width than gate bus lines.
On the other hand, in a liquid crystal display device including an array substrate provided with a protective insulator which is formed between pixel electrodes and some of electrodes of TFTs closer to the pixel electrodes, contact holes are formed in the protective insulator to electrically connect the pixel electrodes and the electrodes of the TFTs.
Therefore, if accuracy in aligning the counter substrate including the spacers with the array substrate is not high, the counter substrate may be misaligned with the array substrate 100, for example, in the direction of an arrow indicated in a schematic plan view of FIG. 10, and therefore the spacers 200 may get into contact holes 300. In such a case, the gap between the array substrate 100 and the counter substrate is not kept uniform, whereby proper display cannot be achieved.
For this reason, measures have been taken so far to arrange the spacers 200 on the counter substrate with high accuracy and to align the counter substrate with the array substrate 100 with as high accuracy as possible.
However, as a pixel pitch has been getting smaller in response to recent demands for high definition, extremely high accuracy is required to align the substrates with each other according to the conventional technique. That is, the problem of great difficulty in aligning the substrates with each other remains unsolved.